A medical imaging apparatus is equipment for acquiring images about the internal structures of objects. The medical imaging apparatus, which is non-invasive examination equipment, scans structural details, internal tissues, and flows of fluid in the human body, processes the results of the scanning, and then displays the processed images for users. A user such as a doctor examines medical images output from such a medical imaging apparatus to diagnose a patient's health status and disease.
A representative one of medical imaging apparatuses for irradiating X-rays onto a patient to scan the patient is a Computed Tomography (CT) apparatus. The CT apparatus can irradiate X-rays onto an object in different directions, and then reconstruct images using a computer. The CT apparatus can image the internal tissues of an object using a fact that different tissues in the object have different attenuation coefficients obtained by digitizing degrees to which the respective tissues absorb or transmit radiation.
Since the CT apparatus can provide section images of an object, it can represent the internal structures (for example, organs, such as kidney, lungs, etc.) of an object such that they do not overlap with each other compared to a general X-ray imaging apparatus. For this reason, the CT apparatus is widely used for precise diagnosis of diseases.
The CT apparatus performs a CT scan on an object to acquire raw data, and uses the raw data to reconstruct a CT image. The raw data may be projection data acquired by projecting X-rays on the object, or a sinogram, which is a group of such projection data.
Before a CT scan is performed on an object, a pre-shot or a scout scan can be performed with a low dose of X-rays in order to control exposure parameters, such as a tube voltage, tube current, an exposure time, the kind and thickness of a filter, a target material of an anode, a focal spot size, etc., which are to be applied to an X-ray source.